Rolling mill third octave chatter control by process damping
AssigneeNovelis Inc.
InventorRodger Brown
Life of this patent
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Abstract
Control of third octave vibrations in a mill stand can be achieved using a high-speed piezoelectric assist coupled to a hydraulic gap cylinder to increase the damping of the roll stack. Vertical movements of the roll stack (e.g., the top work roll) can be determined through observation (e.g., measurement) of hydraulic fluid pressure of the hydraulic cylinder or entry tension of the metal strip. After determining vertical movements of the roll stack, a desired change in hydraulic pressure can be determined to overcome, reduce, or prevent third octave vibration. This desired change in hydraulic pressure can be effectuated at high speeds (e.g., at or above approximately 90 hertz) using the piezoelectric assist.
Claims20
A cold-rolling mill with reduced chatter, comprising:
- a mill stand having a top work roll and a bottom work roll between which a metal strip can be passed, the mill stand comprising a hydraulic cylinder mechanically coupled to provide a rolling force to the top work roll, wherein the mill stand has damping contributing to a process damping associated with using the mill stand to reduce a thickness of the metal strip at a mill speed, and wherein a reduction in the process damping is associated with an increase in the mill speed;
- a piezoelectric assist coupled to the hydraulic cylinder for changing a volume of a fluid chamber of the hydraulic cylinder to introduce additional damping to the process damping;
- and
- a controller coupled to a sensor selected from the group consisting of a pressure sensor of the hydraulic cylinder and a strip tension sensor, wherein the controller is further coupled to the piezoelectric assist for inducing changes in the volume of the fluid chamber in response to linear movement of the top work roll to introduce the additional damping in an amount sufficient to offset the reduction in the process damping and maintain the process damping at a positive amount of damping to avoid third octave chatter of the mill stand.
A method, comprising:
- passing a metal strip between a top work roll and a bottom work roll of a mill stand having damping contributing to a process damping associated with using the mill stand to reduce a thickness of the metal strip at a mill speed, wherein a reduction in the process damping is associated with an increase in the mill speed;
- applying a rolling force to the top work roll by a hydraulic cylinder;
- measuring a parameter of the mill stand, wherein the parameter is a hydraulic pressure of the hydraulic cylinder or an entry tension of the metal strip;
- determining vertical movement of the top work roll using the parameter;
- and
- actuating a piezoelectric assist to change a volume of the hydraulic cylinder in response to the vertical movement of the top work roll to introduce additional damping in an amount sufficient to offset the reduction in the process damping and maintain the process damping at a positive amount of damping to avoid third octave chatter of the mill stand.
A method, comprising:
- passing a metal strip between a top work roll and a bottom work roll of a mill stand having damping contributing to a process damping associated with using the mill stand to reduce a thickness of the metal strip at a mill speed, wherein a reduction in the process damping is associated with an increase in the mill speed;
- applying a rolling force to the top work roll by a hydraulic cylinder having a volume of hydraulic fluid;
- determining vertical movement of the top work roll based on a measurement of pressure of the hydraulic fluid or entry tension of the metal strip;
- and
- supplying supplemental damping to the process damping to avoid third octave chatter of the mill stand, wherein supplying supplemental damping comprises:
- determining an amount of supplemental damping sufficient to offset the reduction in the process damping and maintain the process damping at a positive amount of damping;
- calculating a desired change in the pressure of the hydraulic fluid using the determined amount of supplemental damping;
- and
- applying force to the volume of hydraulic fluid based on the calculated desired change, wherein applying force to the volume of hydraulic fluid comprises actuating a piezoelectric actuator coupled to the hydraulic cylinder.
Dependencies are inferred from the claim text.